A document or currency validator is a device that determines whether checks or bank-note bills are genuine or counterfeit. These devices are used in many automated machines found in retail kiosks, self-checkout machines, gaming machines, transportation parking machines, automatic fare collection machines, vending machines, and the like.
Validation of a document can involve examining the document that has been inserted, and determining if the document is counterfeit. In operation, if the item is accepted it can be retained by the machine and can be placed in a storage container for later collection. If the item is rejected, the machine can return the item.